[Bldg-sim] ASHRAE 2012 Energy Modeling Conference Topic for Discussion
RobertWichert
robert at wichert.org
Tue Sep 4 17:24:46 PDT 2012
How about modelling an uninsulated condenser cooling water line that
runs through the building outside the insulation on the South side of
the building in California?
Robert Wichert P.Eng. LEED AP BD&C
+1 916 966 9060
FAX +1 916 966 9068
===============================================
On 9/4/2012 5:16 PM, Jim Dirkes wrote:
>
> After enjoying all of the posts on this topic, it occurs to me that
> existing energy modeling software is challenged to model certain
> aspects of building operation that are "broken". An example might be a
> chilled or hot water valve which never closes fully.
>
> *James V Dirkes II, PE, BEMP, LEED AP**
> **www.buildingperformanceteam.com*
> <http://www.buildingperformanceteam.com/>*
> **Energy Analysis, Commissioning & Training Services**
> *1631 Acacia Drive, Grand Rapids, MI 49504USA
> 616 450 8653
>
> *From:*Haider Khan [mailto:Haidermkhan at ymail.com]
> *Sent:* Tuesday, September 04, 2012 7:15 PM
> *To:* Ellis, David; Bishop, Bill; Jim Dirkes; Dennis Knight;
> bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] ASHRAE 2012 Energy Modeling Conference Topic
> for Discussion
>
> The key is to not use energy models quantitatively. Energy models
> should generally be used qualitatively to compare to either a known
> benchmark (utility bills for existing buildings etc.) or a baseline
> (regional energy codes for new buildings, etc.). For comparisons to
> utility bills we often model control sequences and other known
> occupant/owner/operator behavior.
>
> Haider Khan.
>
> Engineering Manager, ICF International.
>
> Sent from my iPad
>
>
> On 2012-09-04, at 4:49 PM, "Ellis, David" <David.Ellis at hdrinc.com
> <mailto:David.Ellis at hdrinc.com>> wrote:
>
> Bill, Jim, Dennis, et al
>
> This is a tough nut. In the ESPC or ESCO world, where performance
> must be depended upon to achieve financial returns, there are
> understood and controlling processes in what equipment is bought,
> how it is installed, how it is maintained, how it is operated and
> expected duty schedule. Contracts are written to reduce
> uncertainty to the point that in some cases any deviance, in
> seemly minor matters, throws the performance expectations up for
> renegotiations.
>
> While weather changes can be adjusted for after the fact (and thus
> readily understood as a reason for some differences between real
> and modeled performance), outside of the ESPC/ESCO arena, a design
> engineer/modeler can make their best fine tuned efforts on
> construction intent equipment and operations, to be undone by
> changes in installation, commissioning, operational practices and
> occupancy that are not under their control, and are frequently
> difficult to document after the fact.
>
> In the design arena, modeling is a means to assess options on a
> level plane, and should not be offered as a predictor of actual
> cost unless that risk is fully evaluated and compensated for (both
> in labor/risk fees and in the processes to assure changes are
> documented). There is a real need to fully vet an industry
> standard approach to identifying the risks (for fair negotiation),
> and establishing standards in best practices.
>
> Yes, our modeling does inform sequences of operations, as
> strategies can be involved, and are a combined designer and
> modeler effort. They do indeed make their way into construction
> intent documents ... but implementation and ongoing maintenance
> are another matter.
>
> A calibrated model is an excellent tool for more realistically
> evaluating operational and systems changes. But here too, the
> results should be considered as a way to evaluate options on a
> level playing field, as control over so many variables is out of
> the modelers scope.
>
> I would encourage the development of collective industry guidance
> towards understanding these risks and offering clarification on
> expectations for client informational purposes.
>
> *David Ellis
> *PE (VA, MD, DC)
>
> LEED AP BD+C
>
> CEM
>
> PMP
>
>
>
> *HDR Architecture Inc**
> *Energy Services Technical Director, NC
>
> 1101 King Street, Suite 400 | Alexandria, VA 22314
> 703.647.7735 | c: 703.343.6758
> David.Ellis at hdrinc.com <mailto:first.last at hdrinc.com>|
> hdrarchitecture.com <http://www.hdrinc.com/markets/architecture>
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>
> *From:*Bishop, Bill [mailto:bbishop at pathfinder-ea.com]
> <mailto:[mailto:bbishop at pathfinder-ea.com]>
> *Sent:* Tuesday, September 04, 2012 11:33 AM
> *To:* Jim Dirkes; Dennis Knight; bldg-sim at lists.onebuilding.org
> <mailto:bldg-sim at lists.onebuilding.org>
> *Subject:* Re: [Bldg-sim] ASHRAE 2012 Energy Modeling Conference
> Topic for Discussion
>
> Jim said most of what I was going to say. Additionally,
>
> ·An energy modeler's task for a new construction project is rarely
> to accurately predict energy use, but to demonstrate compliance
> with, and improvement over, code performance.
>
> ·Modelers generally do not fine tune plug loads, occupant numbers
> and schedules etc. because these are kept identical for
> determining improved performance over code.
>
> ·Sequence of operations. The modeler is usually not the engineer
> of record, and should therefore not be dictating the sequence of
> operations of HVAC/plant equipment. I may provide the mechanical
> engineer with suggestions on controls strategies and setpoints,
> and sometimes they are receptive. However, my focus as energy
> modeler is energy, and not comfort, system complexity or
> reliability. Regardless, the exact sequence of operations, even if
> meticulously described in the design documents, may not be
> implemented, or may be changed many times during the first year or
> two of building operation.
>
> ·No/poor commissioning of buildings. Buildings designed to be very
> energy efficient often rely on complex controls for HVAC and
> lighting systems. Many buildings are not commissioned, and even in
> the ones that are, commissioning is often little more than
> verifying that the equipment and controls were installed as
> designed. The commissioning agent rarely has the time/budget/scope
> to determine that all control strategies are operating as
> designed. Also, the commissioning agent cannot change the weather
> conditions during which the building is commissioned, making it
> next to impossible to check CHW controls during winter for example.
>
> ·New buildings often go through many changes in operating
> conditions during their first year or two. New buildings are often
> in use after hours due to people moving into their new offices, or
> because they are nice facilities and the demand to utilize them is
> high.
>
> ·One of the best ways to predict energy performance is data mining
> of existing building performance. Hopefully, CBECS and other
> building performance databases will be a big area of focus for our
> field.
>
> <image001.jpg> <mailto:wbishop at pathfinder-ea.com>
>
> *From:*bldg-sim-bounces at lists.onebuilding.org
> <mailto:bldg-sim-bounces at lists.onebuilding.org>
> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Jim
> Dirkes
> *Sent:* Tuesday, September 04, 2012 10:56 AM
> *To:* Dennis Knight; bldg-sim at lists.onebuilding.org
> <mailto:bldg-sim at lists.onebuilding.org>
> *Subject:* Re: [Bldg-sim] ASHRAE 2012 Energy Modeling Conference
> Topic for Discussion
>
> Dear Dennis and BldgSim Community,
>
> 1.I think the tools are absolutely up to the task. My own
> practice uses EnergyPlus exclusively, but I know that most of the
> other tools are based in solid thermodynamic and physical
> principles -- so they start on a solid foundation.
>
> 2.Current best practices is another story altogether!
>
> a.Keeping in mind that I know only the "Best practices" for my own
> firm ...
>
> b.Energy modelers of new construction are normally given scant
> information.
>
> ·Partly this is due to the owner not knowing exactly how the new
> facility will be used.
>
> ·Partly this is due to the Owner and Designer not caring about,
> not appreciating the importance of, or just not needing to gather
> detailed information about the operation of a building that hasn't
> been built.
>
> ·Partly it's because "as built" is _never_ "as designed". (Think
> of fan and pump pressure estimates differing from actual, weather
> variances, occupancy schedule changes, etc.)
>
> ·The energy modeling community has, it seems, a lot of bright
> young men and women who are "learning the ropes". The fact that
> they are becoming involved is very exciting! Their education must
> be broadened, however, in order for them to become effective at
> modeling _existing_ buildings. It's no longer just theory; there
> is a lot of practical, "hands on" activity that is needed.
>
> 3.Inferred above is the host of variables that differ in an actual
> building's operation from what may have been assumed. The older
> the building, the more variations there are!
>
> 4.Most building operators, if they exist within the building as a
> full time position, are distracted with many other details and
> spent precious little time optimizing energy performance. If
> there is no full time building operator .....
>
> 5.This is a field ripe with opportunity! The first and hardest
> task, I think, is to get building owners convinced that the ROI
> for optimal building performance is better than any of their other
> opportunities for investing. The next task is to streamline the
> process of calibration and identification of opportunities so that
> they is faster and more economical.
>
> 6.... and I'd love to expand this discussion during the Q&A period
> at my presentation on _this topic_ during the ASHRAE Energy
> Modeling Conference!
>
> *James V Dirkes II, PE, BEMP, LEED AP**
> **www.buildingperformanceteam.com*
> <http://www.buildingperformanceteam.com/>*
> **Energy Analysis, Commissioning & Training Services**
> *1631 Acacia Drive, Grand Rapids, MI 49504 USA
> 616 450 8653
>
> *From:*bldg-sim-bounces at lists.onebuilding.org
> <mailto:bldg-sim-bounces at lists.onebuilding.org>
> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of
> *Dennis Knight
> *Sent:* Tuesday, September 04, 2012 10:24 AM
> *To:* bldg-sim at lists.onebuilding.org
> <mailto:bldg-sim at lists.onebuilding.org>
> *Subject:* [Bldg-sim] ASHRAE 2012 Energy Modeling Conference Topic
> for Discussion
>
> I am the Chair of the conference committee for the ASHRAE 2012
> Energy Modeling Conference that will be held in Atlanta on October
> 1, 2 & 3 this year (see link below). The conference is focused on
> bringing practitioners, software developers, researchers and
> facility users together for 3 days of in depth discussion on
> current modeling software capabilities and current best practices
> in energy modeling. I have two questions that I would like to
> pose to this group to get some feedback to help provider richer
> content for the discussions planned at the conference;
>
> 1. Are the current energy modeling tools available to an energy
> modeling practitioner reliable enough to allow the modeler to
> predict a building's actual energy consumption with a high degree
> of confidence such that an accurate energy target can be
> established and recommended to the building owner for the new
> building or a renovation/retrofit?
>
> 2. Are the current best practices of the energy modeling
> community reliable enough, and well understood by most
> practitioners, to allow the modeler to predict a building's actual
> energy consumption with a high degree of confidence such that an
> accurate energy target can be established and recommended to the
> building owner for the new building or a renovation/retrofit?
>
> Background for the discussion:
>
> These questions recently came up in a discussion among the
> conference committee. It seems that one our colleagues from the
> UK indicated that in the UK new schools have performed very poorly
> in comparison with their predicted energy use.
>
> Another comment that was made was as follows:
>
> "Often a building's actual energy consumption is 1.5 to 2 times as
> much as the results of an energy model that was used to make
> decisions during design about the building's energy using systems.
> Is it the the energy modeling tools or is it the processes used
> by energy modelers to describe the systems and how they operate in
> the software? Should energy models be used to "predict" a
> building's future energy performance or just be used to inform
> better decisions during design?
>
> I have reviewed a good many models and, almost without fail, I
> never see a modeler start by writing a sequence of operation and I
> also never see the sequence of operation used by the modeler make
> its way into a set of construction documents.
>
> Also, when I am the modeler and I am "calibrating" a model to an
> existing building's actual energy consumption it is a very
> iterative process. I know what things to manipulate in the model
> to effect demand and what things to manipulate to effect
> consumption. I just keep going back and forth until I have a
> model that you can almost lay its output on top of the building's
> utility bill history. I also have a good understanding of how the
> building is actually being operated and maintained - which I hope
> helps make the model more accurate, but, does that process really
> give me a better model to make decisions from?"
>
> I invite everyone to please, tell us what you think.
>
> Sincerely,
>
> Link to conference webpage:
> http://www.ashrae.org/membership--conferences/conferences/ashrae-conferences/emc2012
>
>
> --
> M. Dennis Knight, P.E.
>
> Founder & CEO
>
> *W*hole *B*uilding *S*ystems, LLC
>
> P.O. Box 1845
>
> Mt. Pleasant, SC 29465
>
> Phone: 843-437-3647
>
> Email: dknight at wholebuildingsystems.com
> <mailto:dknight at wholebuildingsystems.com>
>
> Website: www.wholebuildingsystems.com
> <http://www.wholebuildingsystems.com>
>
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